<!DOCTYPE HTML>
<html class="reftest-wait">
<head>
<style type="text/css"> 
#rear {
	width: 500px;
	height: 1500px;
	box-shadow: 0 0 71px #667;
	display: block;
}
.cover {
    position: absolute;
    width: 520px;
    height: 100px;
    background: yellow;
}
</style>
<script>
function doTest() {
  var es = document.getElementsByClassName("cover");
  for (var i = 0; i < es.length; ++i) {
    es[i].style.display = 'none';
  }
  document.documentElement.removeAttribute("class");
}
window.addEventListener("MozReftestInvalidate", doTest, false);
</script>
</head>
<body>
<div id="rear"></div>
<div class="cover" style="top:100px"></div>
<div class="cover" style="top:300px"></div>
</body>
</html>
